Travellers transporting goods along the Grand Canal, which linked the rich revenue-producing provinces of south China to the capital in Beijing, faced armed robbers, extortionists, and swindlers as they passed through the Capital Region.
As the principal capital of the Ming dynasty, Beijing was at the center of the enormous political, ritual, military, and economic resources associated with the throne.
How are we to explain the rampant banditry in the Capital Region during the middle Ming period?
The Veritable Records were imperially compiled annals with almost daily entries, sometimes multiple entries for each day, comprised of reports from officials in the field and in the capital ministries.
Recently banditry in and around the capital has become rampant.
Mounted banditry continued to be a high-profile crime in the capital region during the first quarter of the sixteenth century, with major outbreaks in 1509-1510,1518, and 1521.
If brigands seemed drawn to Beijing proper, they were also active in many of the entrepots surrounding the capital. Located at the northern terminus of the Grand Canal a dozen miles east of Beijing, Tongzhou was a thriving city during the Ming, boasting specialized markets, periodic markets, and inns "everywhere."  It was also the site of critical imperial rice granaries that supplied the capital.
For instance, in May of 1466, banditry rendered the roads to Beijing impassable, thus severing the capital's supply of rice and sending grain prices spiralling.
In response, imperial military personnel were dispatched: four commanders, chiliarchs, and centurions from the capital were each given 30 skilled cavalry troops to patrol trouble spots around Liangxiang.
It is very likely that less savory members of the Capital Region were also attracted to the excitement of the Medicine King Temple fair.
Gangs of young toughs and beggars were frequently encountered,  and are variously reported to have beaten people, extorted goods, swindled merchants and travellers, and even to have seized grain shipments from soldiers delivering rice to the capital. 
An October report of 1471 gives some indication of the difficulties in transporting goods to the capital. When the Grand Canal froze during the winter months, those delivering grain and goods from the south were forced to resort to overland delivery.